[en] Removing duplicated link on Parallel Programming section
[en] Sorting Parallel programming section
Merge pull request #856 from esparta/master

[en] Cleaning up Parallel Programming section
21'000 !
Isabelle/HOL

Link to current version as described in http://www21.in.tum.de/~nipkow/LNCS2283/
Merge pull request #857 from diekmann/patch-1

Isabelle/HOL
Concrete Semantics - A Proof Assistant Approach
Merge pull request #858 from diekmann/patch-2

Concrete Semantics - A Proof Assistant Approach
[en] Adding book on Open Source section
add angularjs resources
Merge pull request #859 from ngokevin/master

add angularjs resources
Removed dead link in VIM Section
Add Neo4J entry
Merge pull request #861 from jpedro-barbosa/master

Add Neo4J entry
Merge pull request #860 from pshirishreddy/master

Removed dead link in VIM Section
Specify PDF
Add Java EE7 tutorial (PDF)

Add link to the JAVA EE7 Tutorial in the PDF version.
Merge pull request #862 from zeroed/patch-1

Add Java EE7 tutorial (PDF)
Added more Red Gate material

Added the latest Red Gate SQL book, as well as a link to the complete Red Gate "library".
Formatting fix on recent additions